/**
 * \file sha256.h
 *
 * \brief This file contains SHA-224 and SHA-256 definitions and functions.
 *
 * The Secure Hash Algorithms 224 and 256 (SHA-224 and SHA-256) cryptographic
 * hash functions are defined in <em>FIPS 180-4: Secure Hash Standard (SHS)</em>.
 */
/*
 *  Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved
 *  SPDX-License-Identifier: GPL-2.0
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 *  This file is part of Mbed TLS (https://tls.mbed.org)
 */
#ifndef MBEDTLS_SHA256_H
#define MBEDTLS_SHA256_H

#include <stddef.h>
#include <stdint.h>

/* MBEDTLS_ERR_SHA256_HW_ACCEL_FAILED is deprecated and should not be used. */
#define MBEDTLS_ERR_SHA256_HW_ACCEL_FAILED -0x0037 /**< SHA-256 hardware accelerator failed */
#define MBEDTLS_ERR_SHA256_BAD_INPUT_DATA -0x0074  /**< SHA-256 input data was malformed. */

#ifdef __cplusplus
extern "C"
{
#endif

#if !defined(MBEDTLS_SHA256_ALT)
	// Regular implementation
	//

	/**
	 * \brief          The SHA-256 context structure.
	 *
	 *                 The structure is used both for SHA-256 and for SHA-224
	 *                 checksum calculations. The choice between these two is
	 *                 made in the call to mbedtls_sha256_starts_ret().
	 */
	typedef struct mbedtls_sha256_context
	{
		uint32_t total[2];        /*!< The number of Bytes processed.  */
		uint32_t state[8];        /*!< The intermediate digest state.  */
		unsigned char buffer[64]; /*!< The data block being processed. */
		int is224;                /*!< Determines which function to use:
		                               0: Use SHA-256, or 1: Use SHA-224. */
	} mbedtls_sha256_context;

#else /* MBEDTLS_SHA256_ALT */
#include "sha256_alt.h"
#endif /* MBEDTLS_SHA256_ALT */

	/**
	 * \brief          This function initializes a SHA-256 context.
	 *
	 * \param ctx      The SHA-256 context to initialize. This must not be \c NULL.
	 */
	void mbedtls_sha256_init(mbedtls_sha256_context* ctx);

	/**
	 * \brief          This function clears a SHA-256 context.
	 *
	 * \param ctx      The SHA-256 context to clear. This may be \c NULL, in which
	 *                 case this function returns immediately. If it is not \c NULL,
	 *                 it must point to an initialized SHA-256 context.
	 */
	void mbedtls_sha256_free(mbedtls_sha256_context* ctx);

	/**
	 * \brief          This function clones the state of a SHA-256 context.
	 *
	 * \param dst      The destination context. This must be initialized.
	 * \param src      The context to clone. This must be initialized.
	 */
	void mbedtls_sha256_clone(mbedtls_sha256_context* dst,
		const mbedtls_sha256_context* src);

	/**
	 * \brief          This function starts a SHA-224 or SHA-256 checksum
	 *                 calculation.
	 *
	 * \param ctx      The context to use. This must be initialized.
	 * \param is224    This determines which function to use. This must be
	 *                 either \c 0 for SHA-256, or \c 1 for SHA-224.
	 *
	 * \return         \c 0 on success.
	 * \return         A negative error code on failure.
	 */
	int mbedtls_sha256_starts_ret(mbedtls_sha256_context* ctx, int is224);

	/**
	 * \brief          This function feeds an input buffer into an ongoing
	 *                 SHA-256 checksum calculation.
	 *
	 * \param ctx      The SHA-256 context. This must be initialized
	 *                 and have a hash operation started.
	 * \param input    The buffer holding the data. This must be a readable
	 *                 buffer of length \p ilen Bytes.
	 * \param ilen     The length of the input data in Bytes.
	 *
	 * \return         \c 0 on success.
	 * \return         A negative error code on failure.
	 */
	int mbedtls_sha256_update_ret(mbedtls_sha256_context* ctx,
		const unsigned char* input,
		size_t ilen);

	/**
	 * \brief          This function finishes the SHA-256 operation, and writes
	 *                 the result to the output buffer.
	 *
	 * \param ctx      The SHA-256 context. This must be initialized
	 *                 and have a hash operation started.
	 * \param output   The SHA-224 or SHA-256 checksum result.
	 *                 This must be a writable buffer of length \c 32 Bytes.
	 *
	 * \return         \c 0 on success.
	 * \return         A negative error code on failure.
	 */
	int mbedtls_sha256_finish_ret(mbedtls_sha256_context* ctx,
		unsigned char output[32]);

	/**
	 * \brief          This function processes a single data block within
	 *                 the ongoing SHA-256 computation. This function is for
	 *                 internal use only.
	 *
	 * \param ctx      The SHA-256 context. This must be initialized.
	 * \param data     The buffer holding one block of data. This must
	 *                 be a readable buffer of length \c 64 Bytes.
	 *
	 * \return         \c 0 on success.
	 * \return         A negative error code on failure.
	 */
	int mbedtls_internal_sha256_process(mbedtls_sha256_context* ctx,
		const unsigned char data[64]);

#if !defined(MBEDTLS_DEPRECATED_REMOVED)
#if defined(MBEDTLS_DEPRECATED_WARNING)
#define MBEDTLS_DEPRECATED __attribute__((deprecated))
#else
#define MBEDTLS_DEPRECATED
#endif
	/**
	 * \brief          This function starts a SHA-224 or SHA-256 checksum
	 *                 calculation.
	 *
	 * \deprecated     Superseded by mbedtls_sha256_starts_ret() in 2.7.0.
	 *
	 * \param ctx      The context to use. This must be initialized.
	 * \param is224    Determines which function to use. This must be
	 *                 either \c 0 for SHA-256, or \c 1 for SHA-224.
	 */
	MBEDTLS_DEPRECATED void mbedtls_sha256_starts(mbedtls_sha256_context* ctx,
		int is224);

	/**
	 * \brief          This function feeds an input buffer into an ongoing
	 *                 SHA-256 checksum calculation.
	 *
	 * \deprecated     Superseded by mbedtls_sha256_update_ret() in 2.7.0.
	 *
	 * \param ctx      The SHA-256 context to use. This must be
	 *                 initialized and have a hash operation started.
	 * \param input    The buffer holding the data. This must be a readable
	 *                 buffer of length \p ilen Bytes.
	 * \param ilen     The length of the input data in Bytes.
	 */
	MBEDTLS_DEPRECATED void mbedtls_sha256_update(mbedtls_sha256_context* ctx,
		const unsigned char* input,
		size_t ilen);

	/**
	 * \brief          This function finishes the SHA-256 operation, and writes
	 *                 the result to the output buffer.
	 *
	 * \deprecated     Superseded by mbedtls_sha256_finish_ret() in 2.7.0.
	 *
	 * \param ctx      The SHA-256 context. This must be initialized and
	 *                 have a hash operation started.
	 * \param output   The SHA-224 or SHA-256 checksum result. This must be
	 *                 a writable buffer of length \c 32 Bytes.
	 */
	MBEDTLS_DEPRECATED void mbedtls_sha256_finish(mbedtls_sha256_context* ctx,
		unsigned char output[32]);

	/**
	 * \brief          This function processes a single data block within
	 *                 the ongoing SHA-256 computation. This function is for
	 *                 internal use only.
	 *
	 * \deprecated     Superseded by mbedtls_internal_sha256_process() in 2.7.0.
	 *
	 * \param ctx      The SHA-256 context. This must be initialized.
	 * \param data     The buffer holding one block of data. This must be
	 *                 a readable buffer of size \c 64 Bytes.
	 */
	MBEDTLS_DEPRECATED void mbedtls_sha256_process(mbedtls_sha256_context* ctx,
		const unsigned char data[64]);

#undef MBEDTLS_DEPRECATED
#endif /* !MBEDTLS_DEPRECATED_REMOVED */

	/**
	 * \brief          This function calculates the SHA-224 or SHA-256
	 *                 checksum of a buffer.
	 *
	 *                 The function allocates the context, performs the
	 *                 calculation, and frees the context.
	 *
	 *                 The SHA-256 result is calculated as
	 *                 output = SHA-256(input buffer).
	 *
	 * \param input    The buffer holding the data. This must be a readable
	 *                 buffer of length \p ilen Bytes.
	 * \param ilen     The length of the input data in Bytes.
	 * \param output   The SHA-224 or SHA-256 checksum result. This must
	 *                 be a writable buffer of length \c 32 Bytes.
	 * \param is224    Determines which function to use. This must be
	 *                 either \c 0 for SHA-256, or \c 1 for SHA-224.
	 */
	int mbedtls_sha256_ret(const unsigned char* input,
		size_t ilen,
		unsigned char output[32],
		int is224);

#if !defined(MBEDTLS_DEPRECATED_REMOVED)
#if defined(MBEDTLS_DEPRECATED_WARNING)
#define MBEDTLS_DEPRECATED __attribute__((deprecated))
#else
#define MBEDTLS_DEPRECATED
#endif

	/**
	 * \brief          This function calculates the SHA-224 or SHA-256 checksum
	 *                 of a buffer.
	 *
	 *                 The function allocates the context, performs the
	 *                 calculation, and frees the context.
	 *
	 *                 The SHA-256 result is calculated as
	 *                 output = SHA-256(input buffer).
	 *
	 * \deprecated     Superseded by mbedtls_sha256_ret() in 2.7.0.
	 *
	 * \param input    The buffer holding the data. This must be a readable
	 *                 buffer of length \p ilen Bytes.
	 * \param ilen     The length of the input data in Bytes.
	 * \param output   The SHA-224 or SHA-256 checksum result. This must be
	 *                 a writable buffer of length \c 32 Bytes.
	 * \param is224    Determines which function to use. This must be either
	 *                 \c 0 for SHA-256, or \c 1 for SHA-224.
	 */
	MBEDTLS_DEPRECATED void mbedtls_sha256(const unsigned char* input,
		size_t ilen,
		unsigned char output[32],
		int is224);

#undef MBEDTLS_DEPRECATED
#endif /* !MBEDTLS_DEPRECATED_REMOVED */

#ifdef __cplusplus
}
#endif

#endif /* mbedtls_sha256.h */
